Shanghai stocks traded wildly on Thursday morning, as the government beefed up measures to arrest a market slump, dealers said.

The benchmark Shanghai Composite Index fell as much as 3.81 percent before rising up to 2.62 percent. By mid-morning it had gained 0.49 percent, or 17.17 points, to 3,524.36.

The Shenzhen Composite Index, which tracks stocks on China's second exchange, added 2.05 percent, or 38.64 points, to 1,923.09.